How to Fix Wrong Hard Drive Data Usage Calculation in OS X

If you’re running OS X Lion or above, an easy approach to see some quick information about your Mac’s hardware is by selecting “About This Mac” from the Apple menu and then clicking on the “More Information” button. Doing so will open Apple’s System Information tool which can be used to generate a detailed system report. By default, this window will show a brief summary window, which will include a breakdown of storage usage. This is available in the “Storage” tab.

This storage view shows a small chart that breaks down the amount of space used by various audio files, movies, photos, backups, etc. However, sometimes the numbers shown in this window may be incorrect. For example, we’ve seen systems that report 0KB for audio files, even when there were about 100 files present on that particular device.

This issue is simply a result of an incorrect indexing of your hard drive and does represent the true contents of your system. In order for the utility to properly report the space usage, it needs to have a properly built and enabled Spotlight index.

1. Make Sure Spotlight Is On and Indexing Is Enabled

First you need to make sure that Spotlight is enabled for your system. To do this:

1. Open Terminal on your OS X system, and enter the following command:

mdutil -s/

If the result of this command shows “Indexing disabled,” then enable Spotlight by running the following command:

sudo mdutil -i on /

Note: You’ll need an administrator password for sudo commands.

2. Reindex Your Mac’s Hard Drive

The next step is to have the system reindex the hard drive, which can be done in two ways:

Reindex Your Hard Drive Using Spotlight’s Preferences

1. Open System Preferences.

2. Locate and click on “Spotlight”.

3. Click on the “Plus” icon in the Privacy tab.

4. Select your Mac’s hard drive from the left-hand pane. By default, it will be named as “Macintosh HD.”

5. Now, click on the “Minus” button to remove the entry you just made.

After doing so, Spotlight will start to reindex your hard drive.

Reindex Your Mac’s Hard Drive Using Terminal

Alternatively, you can open up Terminal and enter in the following command to force OS X to clear the index and cause the system to rebuild it from scratch:

sudo mdutil -E/

Once you’ve done this, you’ll see the indexing progress bar appear in the Spotlight menu. This may take minutes to hours depending on your system, but once it’s done, the system information utility should properly report file sizes.

Were you facing this issue too? Did the above fix work for you? Be sure to tell us in the comments below.

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